Antenna tower



May 3, 1938. E. J. STAUBITZ 2,116,368

* ANTENNA TOWER Filed July 21, 1936 .;IENTR M,M,M

Patented May 3, 1938 PATENT OFFIQE ANTENNA TOWER Edward J. Staubitz,Pittsburgh, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., acorporation of New Jersey Application July 21, 1936, Serial No. 91,677

I 2 Claims.

This invention relates to structural towers used as radiating antenna.

Vertical radio broadcasting towers made of structural metal are of aheight which is a func- 5 tion of the wave length being broadcast. In

broadcasting in the so-called commercial broadcast band, the height ofthe towers may vary from a few hundred feet to a height of approximatelyone thousand feet. The ideal tower from 0 a structural standpoint is onewhich is of nonuniform cross section as, for instance, the antennadisclosed in Patent No. 1,897,373, to N. Gerten. From the electricalstandpoint, however, it is desirable that the cross-sectional area ofthe tower be substantiallyuniform throughout the height of the antennaand that the crosssectional area be kept as small as possible consistentwith the height of the structure. Many structures have been built as acontinuous unit from top to bottom, using from one set to several setsof guy wires. Considerable difficulty is encountered in calculating thedesign and the stresses of the metal in such a structure. For instance,from a standpoint of the mechanical engineer, when more than one set ofguy wires is used the structure is assumed to be a rigid memher havingthe characteristics of a beam or truss of continuous construction withmore than two supports. The first support is provided at the base andthe succeeding supports are provided by the various sets of guy wires.Such a construction has been accepted as one in which stresses cannot becalculated because there are no formulae which can be used fordefinitely calculating the stresses in various component parts under anycondition of loading. It is quite important, however, that the towerhave the necessary strength to safely maintain itself under allconditions of wind. It is likewise important from 4,0 the electricalstandpoint as well as from. the cost of the tower, that the sizes of thestructural parts; employed be kept at a minimum. There is, therefore, anadvantage in constructing the tower in such manner that the calculationof 4,5 stresses to a reasonably definite extent can be made andmaterials of the proper dimensions used.

The present invention provides an antenna construction of this typewherein the uncertainty 50 of calculation is avoided and wherein thestresses can be determined with reasonable definiteness. At the sametime, the tower provides a structure which for electrical purposes is ofsubstantially uniform cross section throughout its height. 5 Generallyspeaking, the present invention contemplates the construction of thetower in two sections. The lower end of the bottom. section is securedto a pier through a flexible mounting similar to the flexible mountingsnow used for this purpose and as disclosed, for instance, in the 5Gerten patent above referred to, such flexible mounting being a ball andsocket connection. The top of this bottom section is supported by a setof guy wires connected to the tower in a common plane immediatelyadjacent the upper 10 end of the bottom section. This member may then beconsidered as a rigid structure or beam having two points of support, 1.e., one at the bottom where it is anchored and one at the top where theguy wires attach. The upper section 15 of the tower is mounted on thelower one through a non-rigid connection, similar, for instance, to theflexible connection used at the base of the tower. A single set of guywires is connected to this upper section in a plane intermediate thebottom and top of the upper section, preferably at a point above themiddle but well below the top. The upper member is then structurally asimple cantilever, the one point of support being the non-rigidconnection at the top of the bottom section, and the other point ofsupport comprising a set of guy wires attached to the upper section atthe intermediate location.

By this method of construction I obtain a structure which will permitthe calculation of stresses in accordance with the standard practicewhich governs members of this character.

The point of connection between the two sections of the tower requiresthat the adjoining ends of the section be of reduced cross section 35 inorder to accommodate the non-rigid connection between the two sections.This is undesirable from an electrical standpoint, and according to thepresent invention is corrected by the provision of jumpers or conductorswhich span 40 those portions of reduced area, but which are of suchcharacter that they will not serve to transmit mechanical stresses inthe tower structure.

The invention may be readily understood by reference to the accompanyingdrawing, in

which Figure 1 shows a side elevation of a tower constructed inaccordance with my invention;

Figure 2 is a top plan view of the tower shown in Figure 1; and

Figure 3 is a view generally similar to Figure 1, but on a larger scalewith intermediate portions of the tower broken out in order to show moreclearly the. connections.

Referring to the drawing, 2 designates a supporting pier or base onwhich is carried a mounting member 3. The mounting member is hereillustrated as having a spherical end 4 to provide a ball and socketconnection with the base of the tower, but any other type of non-rigidconnection may be provided. The tower itself comprises a bottom section5 formed of structural framework. The lower portion of this sectiontapers down to accommodate a connector or socket 6 for cooperation withthe mounting 3-4 on the pier. Whether or not insulation between thetower and ground is provided in this mounting is a matter which isdetermined by the character of the electrical circuit employed in thebroadcasting station, and insulation may or may not be used as the casemay require. The manner of providing insulation at this point and alsoin the various guy lines is well understood by those skilled in the artand need not be considered in connection with the present invention. Theupper end of the bottom section 5 tapers at 8 to a connector member 9which may have a spherical surface thereon similar to the portion 4 ofthe mounting 3-4. A set of guy wires I U are connected to the upper endof the section 5 adjacent the connector 9.

Supported by the lower section 5 is an upper and longer section II of agenerally similar construction, being formed from structural metalparts. It has a portion I 2 at the lower end thereof that tapers towarda connector I3 cooperating with the connector 9 on the top of the bottomsection. The top of the radiating antenna is designated I4. Secured tothe upper section of the tower intermediate the top and bottom thereofand preferably at a point somewhat above the middle of the uppersection, but well below the top thereof, is a set of guy wires l5, theseguy wires adjoining the tower in a common horizontal plane. The ball andsocket joint 9, [3 provides a non-rigid or flexible connection betweenthe top of the bottom section 5 and the upper section II. Since this isa flexible connection, the bottom section 5 may be considered a rigidstructure within the elasticity of the materials involved, having onepoint of support at the base of the tower and the other point of supportwhere the wires [0 attach thereto. This lower section, of course,carries the weight of the upper section I I. The upper section II havingone point of support at the universal joint 9, l3 and having its otherpoint of support in the plane where the wires l5 attach thereto,comprises a cantilever. If the connection 9, l3 were a rigid connection,then the stress distribution in the tower would present an entirelydifferent problem and the structure would be one wherein there is noformula for calculating stresses.

The provision of a non-rigid or flexible connection between the twosections requires the tapering off in the cross-sectional area of thetwo sections to the single point of connection. This is undesirable froman electrical standpoint for the reason that the radiator is intended tobe energized with electrical currents of radio frequencies, and it isimportant that the crosssectional form of the structure be maintainedthroughout the height in order to permit radiation in a normal manner.To overcome the variation in cross section imposed by the provision ofthe flexible or non-rigid connection 9, I3, I provide several jumpers I6of conducting material to maintain electrically the straight-sidedcontour of the tower. These jumpers, however, are flexible or of suchphysical character or dimensions that no mechanical strain will betransmitted through the jumpers from one section of the tower to anotherunder any condition of loading. The jumpers are preferably located so asto form continuations of the legs of the tower across the distance wherethe adjoining ends of the two sections taper.

The drawing illustrates the tower as being of triangular cross section.This is merely for the purpose of illustration, and it will beunderstood that the tower may be square, round or have any othercross-sectional form that may be required or may be suitable from thestandpoint of design.

While I have illustrated one specific embodiment of my invention and oneparticular form of flexible connection, it will be understood that thisis merely by way of illustration and that the invention may be variouslyembodied and that various modifications and changes may be made in theconstruction shown.

I claim:

1. A tower antenna comprising a vertical bottom section formed ofstructural metal anchored at its lower end and supported at its upperend by guy wires attached thereto, an upper vertical section formed ofstructural metal carried on the lower section by a flexible coupling,said upper section being supported by guy wires attached thereto in acommon plane intermediate the top and bottom of the upper section, thecross-sectional area of the two sections of the tower diminishing towardsaid flexible connection, and electrical jumpers across such areas ofreduced cross section maintaining the contour of the tower forelectrical purposes but not capable of functioning to transmit stresses.

2. A tower antenna having upper and lower structural sections of metalcomprised of uprights and cross bracing, a flexible coupling between thetwo sections, the top of the lower section and the bottom of the uppersection tapering inwardly toward the flexible connection whereby thecontinuity of the contour of the structure is interrupted adjacent thecoupling, and flexible metallic jumpers connecting the two sectionsaround the flexible coupling and the tapered end portions which maintainthe continuity of the contour of the tower for electrical purposes, butare incapable of functioning to transmit stresses from one section tothe other, the structure as a whole constituting a linear radiator.

EDWARD J. STAUBITZ.

